Business data communications 4e chapter 3

Chapter 3 : Distributed Data Processing Business Data Communications, 4e... Centralized Data Processing✘ Centralized computers, processing, data, control, support ✘ What are the advantag

Chapter 3 : Distributed Data Processing

Business Data Communications, 4e

Centralized Data Processing

✘ Centralized computers, processing, data, control, support

✘ What are the advantages?

✘ Economies of scale (equipment and personnel)

✘ Lack of duplication

✘ Ease in enforcing standards, security

Distributed Data Processing

✘ Computers are dispersed throughout organization

✘ Allows greater flexibility in meeting individual needs

✘ More redundancy

✘ More autonomy

Why is DDP Increasing?

✘ Dramatically reduced workstation costs

✘ Improved user interfaces and desktop power

✘ Ability to share data across multiple servers

DDP Pros & Cons

✘ There are no “one-size-fits-all” solutions

✘ Key issues

✘ How does it affect end-users?

✘ How does it affect management?

✘ How does it affect productivity?

✘ How does it affect bottom-line?

Benefits of DDP

✘ Responsiveness

✘ Availability

✘ Correspondence to Org

Patterns

✘ Resource Sharing

✘ Incremental Growth

✘ Increased User

Involvement & Control

✘ End-user Productivity

✘ Distance & location independence

✘ Privacy and security

✘ Vendor independence

✘ Flexibility

Drawbacks of DDP

✘ More difficulty test & failure diagnosis

✘ More components and dependence on communication means more points of failure

✘ Incompatibility of components

✘ Incompatibility of data

✘ More complex management & control

✘ Difficulty controlling information resources

✘ Suboptimal procurement

✘ Duplication of effort

Reasons for DDP

✘ Need for new applications

✘ On large centralized systems, development can take years

✘ On small distributed systems, development can be component-based and very fast

✘ Need for short response time

✘ Centralized systems result in contention among users and processes

✘ Distributed systems provide dedicated resources

The DP “Pendulum”

✘ Centralized systems (mainframes, etc)

✘ Distributed systems (PCs)

✘ Networked systems

✘ Client-Server computing

Client/Server Architecture

✘ Combines advantages of distributed and

centralized computing

✘ Cost-effective, achieves economies of scale

✘ Flexible, scalable approach

✘ Uses Internet-based standards & TCP/IP

✘ Content is accessible only to internal users

✘ A specialized form of client/server

architecture

✘ Similar to intranet, but provides access to controlled number of outside users

✘ Vendors/suppliers

✘ Customers

Distributed applications

✘ Horizontal partitioning

✘ Different applications on different systems

✘ One application replicated on systems

✘ Example: Office automation

✘ Vertical partitioning

✘ One application dispersed among systems

✘ Example: Retail chain POS, inventory, analysis

Distributed data

✘ Centralized database

✘ Pro: No duplication of data

✘ Con: Contention for access

✘ Replicated database

✘ Pro: No contention

✘ Con: High storage and data reorg/update costs

✘ Partitioned database

✘ Pro: No duplication, limited contention

✘ Con: Ad hoc reports more difficult to assemble

Networking Implications

✘ Connectivity requirements

✘ What links between components are necessary?

✘ Availability requirements

✘ Percentage of time application or data is available to users

✘ Performance requirements

✘ Response time requirements